Blackwell: Risk and Relevance of Lithium

Comment by Gordon Johnson

The report on serious treatment emergent adverse effects with lithium in JAMA with over 50% requiring hospitalisation is a wakeup call on the clinical practice of lithium usage. Adequate monitoring including plasma levels has been rightly emphasised by Blackwell. Optimum plasma levels for maintenance of bipolar disorder balancing effectiveness and tolerability vary but can be achieved for the majority of patients with levels of 0.6-0.8 mEq/L. This can be adjusted: bear in mind that levels above 0.8 increase the risk of adverse effects. Level of 1.0 mEq/L or above require review of risk/benefit. Levels below O.6 mEq/L may be less effective.

Adverse effects during maintenance may be insidious but symptoms that should alert the clinician to impending intoxication are progressive weakness, difficulty in thinking and concentration, increased tremor, unsteadiness, and an increased thirst. Lithium intoxication can occur with plasma levels within the therapeutic range emphasising the importance of clinical monitoring as well.

The frequency of plasma monitoring will depend on mood stability, compliance, potential drug interactions, older age with decreasing renal function and reduced lithium excretion, with dosage adjustment and adverse effects.  Routine frequency of plasma monitoring would range from each 3-6 months.  Plasma levels should be standardised, taken in the morning 12-14 hours after the last dose in the evening.

Lithium remains the first line treatment for maintenance in patients with bipolar disorder. Safety issues arise when appropriate clinical and plasma monitoring is ignored. This is an educational and training issue, not confined to the USA that has an impact on the use of lithium by the clinician and acceptance by the patient

Gordon Johnson

August 13, 2015